drivers/firmware/efi/libstub/kaslr.c

Source file repositories/reference/linux-study-clean/drivers/firmware/efi/libstub/kaslr.c

File Facts

System
Linux kernel
Corpus path
drivers/firmware/efi/libstub/kaslr.c
Extension
.c
Size
4708 bytes
Lines
158
Domain
Driver Families
Bucket
drivers/firmware
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

if (base >= md->phys_addr && base < end) {
			ret = (base + size) <= end;
			break;
		}
	}

	return ret;
}

/**
 * efi_kaslr_relocate_kernel() - Relocate the kernel (random if KASLR enabled)
 * @image_addr: Pointer to the current kernel location
 * @reserve_addr:	Pointer to the relocated kernel location
 * @reserve_size:	Size of the relocated kernel
 * @kernel_size:	Size of the text + data
 * @kernel_codesize:	Size of the text
 * @kernel_memsize:	Size of the text + data + bss
 * @phys_seed:		Random seed used for the relocation
 *
 * If KASLR is not enabled, this function relocates the kernel to a fixed
 * address (or leave it as its current location). If KASLR is enabled, the
 * kernel physical location is randomized using the seed in parameter.
 *
 * Return:	status code, EFI_SUCCESS if relocation is successful
 */
efi_status_t efi_kaslr_relocate_kernel(unsigned long *image_addr,
				       unsigned long *reserve_addr,
				       unsigned long *reserve_size,
				       unsigned long kernel_size,
				       unsigned long kernel_codesize,
				       unsigned long kernel_memsize,
				       u32 phys_seed)
{
	efi_status_t status;
	u64 min_kimg_align = efi_get_kimg_min_align();

	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) {
		/*
		 * If KASLR is enabled, and we have some randomness available,
		 * locate the kernel at a randomized offset in physical memory.
		 */
		status = efi_random_alloc(*reserve_size, min_kimg_align,
					  reserve_addr, phys_seed,
					  EFI_LOADER_CODE, 0, EFI_ALLOC_LIMIT);
		if (status != EFI_SUCCESS)
			efi_warn("efi_random_alloc() failed: 0x%lx\n", status);
	} else {
		status = EFI_OUT_OF_RESOURCES;
	}

	if (status != EFI_SUCCESS) {
		if (!check_image_region(*image_addr, kernel_memsize)) {
			efi_err("FIRMWARE BUG: Image BSS overlaps adjacent EFI memory region\n");
		} else if (IS_ALIGNED(*image_addr, min_kimg_align) &&
			   (unsigned long)_end < EFI_ALLOC_LIMIT) {
			/*
			 * Just execute from wherever we were loaded by the
			 * UEFI PE/COFF loader if the placement is suitable.
			 */
			*reserve_size = 0;
			return EFI_SUCCESS;
		}

		status = efi_allocate_pages_aligned(*reserve_size, reserve_addr,
						    ULONG_MAX, min_kimg_align,
						    EFI_LOADER_CODE);

		if (status != EFI_SUCCESS) {
			efi_err("Failed to relocate kernel\n");
			*reserve_size = 0;
			return status;
		}
	}

	memcpy((void *)*reserve_addr, (void *)*image_addr, kernel_size);
	*image_addr = *reserve_addr;
	efi_icache_sync(*image_addr, *image_addr + kernel_codesize);
	efi_remap_image(*image_addr, *reserve_size, kernel_codesize);

	return status;
}

Annotation

Implementation Notes